What they're saying about franchises vs developers is completely true, and I have seen it with my own eyes!
One of my favorite game series Spyro the Dragon from the original Playstation had this problem happen to it after the 3rd game The Year of the Dragon. It got a sequel on the Playstation 2 later, but not made by Insomniac the ones who created it. It was Year of the Dragonfly, and pretty much whatever bad sequel thing you can name it had. Even though it was on a new system it somehow ended up looking terrible even in comparison to the first, and Spyro the Dragon was a very early game on the original Playstation!
If the game's sequel isn't worked on by the same people that worked on the one before, I can tell you from personal experience that's not a good sign.
One of my favorite game series Spyro the Dragon from the original Playstation had this problem happen to it after the 3rd game The Year of the Dragon. It got a sequel on the Playstation 2 later, but not made by Insomniac the ones who created it. It was Year of the Dragonfly, and pretty much whatever bad sequel thing you can name it had. Even though it was on a new system it somehow ended up looking terrible even in comparison to the first, and Spyro the Dragon was a very early game on the original Playstation!
If the game's sequel isn't worked on by the same people that worked on the one before, I can tell you from personal experience that's not a good sign.